DESCRIPTION: Recently, computer based videokeratography (VK) has become important for measuring corneal shape before and after refractive surgery and in diagnosing keratoconus. Regrettably, present algorithms are flawed because they assume light rays that form the VK image lie in the meridional plane before and after reflection from the cornea. For both keratoconus and refractive surgery this assumption can produce substantial errors. The investigators have begun development of a new algorithm that eliminates such errors. There are a number of topic on which further research is needed before the algorithm is viable. The investigators will also develop software for splicing and averaging multiple shots to extend coverage to the whole cornea and to reduce noise. Also, they will develop two end-user applications: 1) Software for fitting hard and soft toric contact lens (for correction of astigmatism) that will take into account corneal topography to achieve improved lens centration and orientation. They expect to develop the first successful contact lens fitting software, enabling VK to become a standard instrument for contact lens fitting. Presently several thousand videokeratoscope instruments are being used for refractive surgery and for diagnosing keratoconus. The number of instruments will expand rapidly if improved algorithms for measuring corneal shape and improved applications software become available. As one example, the market for a clinically superior contact lens fitting package in very large (especially true for the many countries with few trained contact lens specialists). The investigators expect that software will be the first to win clinical approval.